1. Field of the Invention
The present invention relates to a reception apparatus and a reception processing method, and more particularly, is suitably applied, for example, to a cellular phone in a digital cellular phone system.
2. Description of the Related Art
In recent years, the market of the mobile communication field is expanding drastically. However, fading is one of the problems specific to a digital cellular phone system using radio.
This fading occurs on a transmission path whose state changes every moment influenced by natural phenomena and structures, etc. When a cellular phone receiving a number of different radio waves is moving, due to a Doppler effect, the frequency of a radio wave coming from ahead increases while the frequency of a radio wave coming from behind decreases and fading is a phenomenon that the reception level fluctuates because the amplitude and phase are distorted when these radio waves are received and combined, which can cause deterioration of transmission quality.
In order to compensate the deterioration of transmission quality due to such fading, in a mobile communication system, a base station on the transmitting side performs, for example, convolution coding on transmission data and rearranges data by interleaving and generates an information symbol group by performing modulation processing on a resultant coding bit string.
Then, the base station adds a plurality of pilot symbols as a header at the start of each frame from the information symbol group and performs filtering processing, digital/analog conversion processing and frequency conversion processing on a resultant transmission symbol group and thereby creates a transmission signal of a predetermined frequency channel and transmits the signal via an antenna to cellular phones.
By the way, the pilot symbol added here is a symbol with a known patter, which is already known to a cellular phone on the receiving side, and the cellular phone can estimate the fading characteristic by comparing the pilot symbol with the known pattern and the pilot symbol of the reception data.
The cellular phone with such a configuration has a fading characteristic, which drastically changes according to the traveling speed, but has been unable to accurately control the fading characteristic according to the traveling speed.
Because of this, the cellular phone cannot execute optimal reception processing for every traveling speed and has a problem of having difficulty in compensating the deterioration of transmission quality due to fading that changes according to the traveling speed and improving the reception characteristic.
In view of the foregoing, an object of this invention is to provide a reception apparatus and a reception processing method capable of compensating the deterioration of transmission quality independently of the traveling speed and improving the reception characteristic.
The foregoing object and other objects of the invention have been achieved by the provision of a reception apparatus which receives a transmission signal sent via a radio transmission path, carries out various kinds of reception processing on the received signal and demodulates data, can perform optimal reception processing on the radio transmission path whose state changes according to the traveling speed of the terminal itself by receiving traveling speed information from speed detection means that detects the traveling speed of the terminal itself and controlling reception processing on the reception signal according to the traveling speed information.
The nature, principle and utility of the invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings in which like parts are designated by like reference numerals or characters.